20 February 2013

Faulkes Z. 2012. How much is that crayfish in the window? Online monitoring of Marmorkrebs, Procambarus fallax f. virginalis (Hagen, 1870) in the North American pet trade. Freshwater Crayfish19(1): 39-44. http://dx.doi.org/10.5869/fc.2013.v19.039

Abstract

Marmorkrebs were discovered by European pet owners in the 1990s. Because there is no known native population of Marmorkrebs, the distribution of these crayfish is purely the result of human activity. Marmorkrebs are now spread throughout the pet trade worldwide and are introduced species in several countries. Given that the pet trade has been the suspected or confirmed source of introduction of many introduced species, I monitored online social activity for information about the use and spread of Marmorkrebs in North America. This revealed several new jurisdictions where Marmorkrebs had not been previously reported. Several records were found in jurisdictions where the local laws prohibited the owners from having Marmorkrebs. Tracking such records could be useful in determining the risk of Marmorkrebs introductions from release by pet owners.

18 February 2013

we sadly have to inform you that yesterday our dear friend and colleague Francesca Gherardi passed away.

It was only weeks ago that I met Dr. Gherardi for the first time at the Society for Integrative and Comparative Biology meeting, where she was a speaker at the special session on crayfish. She was having terrible problems with her throat. She could barely whisper, but this did not diminish her presentation, once she got her hands on the microphone.

12 February 2013

I have to thank Nicole Gugliucci. Over the weekend, I was participating a a Google Plus hangout with Nicole and a few other people, describing some of the research I’ve been doing on the pet trade in Marmorkrebs. I made a comment like, “If you have Marmorkrebs as a pet, you always end up with surplus, because you can’t stop them from reproducing.”

I was stunned. Marmorkrebs are totally like tribbles! How could I not have realized this before?

Dr. McCoy: [on reasons for the tribbles' high reproduction rate] Well, the nearest thing I can figure out is that they're born pregnant. Which seems to be quite a time saver.

Indeed, the original episode, “The Trouble With Tribbles,” contains this bit of dialogue that could be applied to any number of invasive species:

Spock: Surely you must have realized what would happen if you removed the tribbles from their predator-filled environment into an environment where their natural multiplicative proclivities would have no restraining factors.Cyrano Jones: [all in one breath] Well, of cour... What did you say?Spock: [irritated but patient] By removing the tribbles from their natural habitat, you have, so to speak, removed the cork from the bottle and allowed the genie to escape.

Phylogenetic relationships within decapod crustaceans are highly controversial. Even recent analyses based on molecular datasets have shown largely contradictory results. Previous studies using mitochondrial genomes are promising but suffer from a poor and unbalanced taxon sampling. To fill these gaps we sequenced the (nearly) complete mitochondrial genomes of 13 decapod species: Stenopus hispidus, Polycheles typhlops, Panulirus versicolor, Scyllarides latus, Enoplometopus occidentalis, Homarus gammarus, Procambarus fallax f. virginalis, Upogebia major, Neaxius acanthus, Calocaris macandreae, Corallianassa coutierei, Cryptolithodes sitchensis, Neopetrolisthes maculatus, and add that of Dromia personata. Our new data allow for comprehensive analyses of decapod phylogeny using the mitochondrial genomes of 50 species covering all major taxa of the Decapoda. Five species of Stomatopoda and one species of Euphausiacea serve as outgroups. Most of our analyses using Maximum Likelihood (ML) and Bayesian inference (BI) of nucleotide and amino acid datasets revealed congruent topologies for higher level decapod relationships: (((((((Anomala, Brachyura), Thalassinida: Gebiidea), Thalassinida: Axiidea), (Astacidea, Polychelida), Achelata), Stenopodidea), Caridea), Dendrobranchiata). This result corroborates several traditional morphological views and adds new perspectives. In particular, the position of Polychelida is surprising. Nevertheless, some problems can be identified. In a minority of analyses the basal branching of Reptantia is not fully resolved, Thalassinida are monophyletic; Polychelida are the sister group to Achelata, and Stenopodidea are resolved as sister group to Caridea. Despite this and although some nodal supports are low in our phylogenetic trees, we think that the largely stable topology of the trees regardless of different types of analyses suggests that mitochondrial genomes show good potential to resolve the relationship within Decapoda.

Crustaceans can store excess copper in the hepatopancreas, an organ playing a role in digestive activity as well as in neurosecretory control. Here, we studied the effect of copper exposure on the level of histamine, an indicator of food spoilage in edible crustaceans. Histamine is also a neuromodulator in the intestinal nervous system of crustaceans, and a human allergen. Marbled crayfish (Procambarus fallax forma virginalis) were exposed to average measured values of 0.031 mg Cu/l and 0.38 mg Cu/l, respectively, for 14 days and then transferred to copper-free water for another 14 days. Concentrations of copper and histamine in the hepatopancreas and muscle were evaluated at different time points. Histamine levels were significantly higher in hepatopancreas and muscle tissues at the highest exposure level, but only after transfer of the animals to copper-free water. The increased histamine concentration following copper exposure may be explained by a (delayed) stress response, and by up-regulated histidine synthesis induced by copper, followed by decarboxylation to histamine.